1. Field of the Invention
The present invention relates to a power transfer system and method for a vehicle, such as a hybrid vehicle, and a vehicle using the same.
2. Background Art
With reference to FIG. 1, a cross-sectional schematic diagram is provided of a conventional power transfer system 10 corresponding to a vehicle having an electric motor 40 configured to drive a plurality of wheels 36 (e.g., a hybrid electric vehicle, a pure electric vehicle and/or the like). As illustrated, the electric machine, or motor 40, may be used to output torque to a shaft (i.e., rotor shaft) 42 which, in turn, is connected to the plurality of vehicle drive wheels 36 through a gear set 38, a shaft 60, a differential unit 62, and a plurality of half axles 64. In general, the gear set 38 may be coupled to one or more other components (i.e., in addition to the motor 40) as represented generally by the shaft 34. The motor 40 is generally powered from an energy power source, such as a high voltage battery (not shown).
As further illustrated in FIG. 1, one or more bearing sets 80 (e.g., 80a and 80b) are generally implemented in connection with the power transfer system 10. In particular, the bearing sets 80a and 80b are generally implemented to center the rotor shaft 42 on a housing of the motor 40. Each of the bearing sets 80a and 80b have a grounded outer race, such as an outer race fixed to the housing. Accordingly, to avoid excessive wear and/or premature failure of the bearing sets 80a and 80b, each of the bearing sets 80a and 80b must be rated at the maximum rotational speed (i.e., max Ws) of the motor 40.
It may be desirable, therefore, to have a power transfer system and/or method wherein the rating of one or more bearing set (e.g., 80a and/or 80b) may be reduced. Such a reduction in the rating of one or more bearing set may decrease the cost of an associated power transfer system as the cost of manufacturing and/or obtaining bearings is generally proportional to the rating of the bearings.